Table 2 Details of study quality evaluation via the Cochrane’s Risk of Bias Tool
| Â | Sequence generation | Allocation concealment | Blinding of participants and personnel | Blinding of outcome assessment | Incomplete outcome data | Selective outcome reporting | Other potential threats | Total |
|---|---|---|---|---|---|---|---|---|
Meltzer 2000 | Low | Unclear | Low | Low | Low | Low | Unclear | 5 |
Nayak 2002 | Low | Unclear | Low | Low | Low | Low | Low | 6 |
Philip 2002 | Unclear | Unclear | Low | Low | Low | Low | Unclear | 4 |
van Adelsberg 2003a | Low | Unclear | Low | Low | Low | Low | Unclear | 5 |
van Adelsberg 2003b | Unclear | Unclear | Low | Low | Low | Low | Unclear | 4 |
Lee 2004 | Unclear | Unclear | Low | Low | Low | Low | Unclear | 4 |
Di Lorenzo 2004 | Unclear | Unclear | Low | Low | Low | Low | Low | 5 |
Hsieh 2004 | Low | Unclear | Low | Low | Low | Low | Unclear | 5 |
Ciebiada 2006-levo | Unclear | Unclear | Low | Low | Low | Unclear | Unclear | 3 |
Ciebiada 2006-deslo | Unclear | Unclear | Low | Low | Low | Unclear | Unclear | 3 |
Jiang 2006 | Low | Unclear | High | High | Low | Low | Unclear | 3 |
Philip 2007 | Low | Unclear | Low | Low | Low | Low | Unclear | 5 |
Lu 2009-1 | Low | Unclear | Low | Low | Low | Low | Low | 6 |
Lu 2009-2 | Low | Unclear | Low | Low | Low | Low | Low | 6 |
Liu 2016 | Unclear | Unclear | High | High | Low | Low | Unclear | 2 |
Jia 2017 | Unclear | Unclear | High | High | Low | Low | Unclear | 2 |